Cardiotoxicity is a major concern to pharmaceutical industry and regulatory agencies. Drugs are cntinuosly removed from the market because their toxic effects. To avoid cardiovascular side effects, regulatory agencies generated guidelines describing preclinical investigation to be performed before initiating clinical trials. These tests are often labor intensive and are conducted during the late stage of drug discovery, causing severe financial osses in case of safety issues. Thus, the development of a High-Throughput assay to be conducted during the early phase of drug devleopment will reduce the overall cst of new drug development. The proposal will develop a human iPS cell line with a selectable marker for cardiac lineage differentiation and luciferase expression. Human cardiomyocytes, derived by the engineered iPS cells, will be used in combination with an autimatic Calcium Transient Image Cytometer (CTIC) to analyse calcium transient and ATP in 384 well format plates. These parameters are altered when cardiomyocytes are exposed to compound that are either arrhythmogenic or toxic. The assay will identify compounds potentially interested by safety heart concerns, increasing the safety of drugs that otherwise will be released on the market, threatening the public health.